Mechanically flexible low-leakage multilayer gate dielectrics for flexible organic thin film transistors

Abstract

The incorporation of an ultrathin, atomic layer deposited HfO2 layer in between the spin-coated poly-4-vinyl phenol (PVP) organic layers in the laminated multilayer gate dielectric for pentacene organic thin film transistors on a flexible substrate reduced the gate leakage current by three to four orders of magnitude and thereby significantly enhanced the current on/off ratio up to ≅104-fold. Cyclic bending testing indicated that the electrical characteristics of the device with the PVP∕HfO2∕PVP trilayer gate dielectric stack were superior to those of the device with the single PVP gate dielectrics due to the improved mechanical and electrical stabilities of the gate dielectric.

Preparation and properties of BaTiO3 filled butyl rubber composites for flexible electronic circuit applications

“…The flexible substrates have many potential applications from neural prosthetics in the medical field to microwave devices in electronics. Pliable substrates provide the advantage of three-dimensional designs of conformal structures [3,4]. The requirements of a material to be used for flexible substrate applications are low relative permittivity, low loss tangent, low coefficient of thermal expansion (CTE), high thermal conductivity, good mechanical flexibility, moisture absorption resistance etc.…”

Solution processed molecular floating gate for flexible flash memories

“…The organic/inorganic bilayer dielectric structure used in our device can reduce the possibility of cracking or delamination during repetitive bending53. Flexibility tests using cyclic bending were performed both in tensile and compressive mode with a bending radius of 10 mm.…”

Improved electrical stability in cyclically bent organic thin film transistors with nanocomposite gate dielectrics and surface passivation

“…[5][6][7] The electrical stability of cyclically bent OTFTs is affected by the mechanical integrity of the active and passive materials, as well as by their interfaces in multilayered hybrid or entirely organic OTFT device structures. 6,7 Changes in leakage current, current on/off ratio ͑I on / I off ͒, threshold voltage ͑V th ͒, and hysteresis ͑⌬V hys ͒ of flexible OTFTs under repetitive mechanical deformation need to be minimized for their practical application in flexible systems.…”

“…[5][6][7] The electrical stability of cyclically bent OTFTs is affected by the mechanical integrity of the active and passive materials, as well as by their interfaces in multilayered hybrid or entirely organic OTFT device structures. 6,7 Changes in leakage current, current on/off ratio ͑I on / I off ͒, threshold voltage ͑V th ͒, and hysteresis ͑⌬V hys ͒ of flexible OTFTs under repetitive mechanical deformation need to be minimized for their practical application in flexible systems. Despite recent progress to improve the electrical stabilities in unbent OTFTs, [8][9][10][11][12][13][14][15][16][17][18][19] only a few studies concerning the electrical stabilities of cyclically bent OTFTs or efforts to improve their stabilities under cyclic bending have been reported.…”

“…Despite recent progress to improve the electrical stabilities in unbent OTFTs, [8][9][10][11][12][13][14][15][16][17][18][19] only a few studies concerning the electrical stabilities of cyclically bent OTFTs or efforts to improve their stabilities under cyclic bending have been reported. 6,7 For example, our research group has shown that leakage currents, I on / I off , and V th of cyclically bent flexible OTFTs can be stabilized by utilizing nanostructured gate dielectrics. 6,7 However, it was found that the on-state and off-state currents were increased significantly due to accelerated degradation of the pentacene layer during cyclic bending.…”